If you have created a warranty job, but when viewing the proforma or invoice, there are no values showing, this will likely be caused by the warranty set up.
A warranty job uses the vehicle make against the job to pull through the costs, these are set up within Service Parameters > Labour rates > Warranty Rates. This is the first point of call to check when the costs aren't showing on the job, you'll need to ensure the make against the job has values entered against the below screen, attached is a link to the help page on how to amend warranty rates in further detail.